<template>
    <div class="music-list">
        <div class="back" @click="back">
            <i class="icon-back"></i>
        </div>
        <h1 class="title" v-html="title"></h1>
        <div class="bg-image" :style="bgStyle" ref="bgImage">
            <div class="play-wrapper">
                <div ref="playBtn" v-show="songs.length > 0" class="play" @click="random">
                    <i class="icon-play"></i>
                    <span class="text">随机播放全部</span>
                </div>
            </div>
            <div class="filter" ref="filter"></div>
        </div>
        <div class="bg-layer" ref="layer"></div>
        <Scroll @scroll="scroll"
                :probe-type="probeType"
                :listen-scroll="listenScroll"
                :data="songs"
                class="list"
                ref="list">
            <div class="song-list-wrapper">
                <SongList :songs="songs" :rank="rank" @select="selectItem"></SongList>
            </div>
            <div class="loading-container" v-show="!songs.length">
                <Loading></Loading>
            </div>
        </Scroll>
    </div>
</template>

<script type="text/ecmascript-6">
import Scroll from 'base/Scroll/Scroll'
import SongList from 'base/SongList/SongList'
import Loading from 'base/Loading/Loading'
import {prefixStyle} from 'common/js/dom'
import {mapActions} from 'vuex'
import { playListMixin } from 'common/js/mixin'

const RESERVED_HEIGHT = 40
const transform = prefixStyle('transform')
const backdrop = prefixStyle('backdrop-filter')

export default {
    mixins: [playListMixin],
    props : {
        bgImage : {
            type : String,
            default : ''
        },
        songs : {
            type : Array,
            default : ''
        },
        title : {
            type : String,
            default : ''
        },
        rank : {
            type : Boolean,
            default : false
        }
    },
    data () {
        return {
            scrollY : 0
        }
    },
    created () {
        this.probeType = 3
        this.listenScroll = true
    },
    computed : {
        bgStyle () {
            return `background-image:url(${this.bgImage})`
        }
    },
    mounted () {
        this.imageHeight = this.$refs.bgImage.clientHeight
        this.minTransalteY = -this.imageHeight + RESERVED_HEIGHT
        this.$refs.list.$el.style.top = `${this.$refs.bgImage.clientHeight}px`
    },
    methods : {
        handlePlayList (playlist) {
            const bottom = playlist.length > 0 ? '60px' : ''
            this.$refs.list.$el.style.bottom = bottom
            this.$refs.list.refresh()
        },
        back () {
            this.$router.back()
        },
        scroll (pos) {
            this.scrollY = pos.y
        },
        selectItem(item, index) {
            this.selectPlay({
                list : this.songs,
                index
            })
        },
        random () {
            this.randomPlay({
                list : this.songs
            })
        },
        ...mapActions([
            'selectPlay',
            'randomPlay'
        ])
    },
    watch: {
        scrollY(newVal) {
            let translateY = Math.max(this.minTransalteY, newVal)
            let scale = 1
            let zIndex = 0
            const percent = Math.abs(newVal / this.imageHeight)
            if (newVal > 0) {
                scale = 1 + percent
                zIndex = 10
            }
            this.$refs.layer.style[transform] = `translate3d(0,${translateY}px,0)`
            if (newVal < this.minTransalteY) {
                zIndex = 10
                this.$refs.bgImage.style.paddingTop = 0
                this.$refs.bgImage.style.height = `${RESERVED_HEIGHT}px`
                this.$refs.playBtn.style.display = 'none'
            } else {
                this.$refs.bgImage.style.paddingTop = '70%'
                this.$refs.bgImage.style.height = 0
                this.$refs.playBtn.style.display = ''
            }
            // 下拉背景图片伸缩
            this.$refs.bgImage.style[transform] = `scale(${scale})`
            this.$refs.bgImage.style.zIndex = zIndex
      }
    },
    components : {
        Scroll,
        SongList,
        Loading
    }
}
</script>

<style scoped lang="stylus" rel="stylesheet/stylus">
  @import "~common/stylus/variable"
  @import "~common/stylus/mixin"

  .music-list
    position: fixed
    z-index: 100
    top: 0
    left: 0
    bottom: 0
    right: 0
    background: $color-background
    .back
      position absolute
      top: 0
      left: 6px
      z-index: 50
      .icon-back
        display: block
        padding: 10px
        font-size: $font-size-large-x
        color: $color-theme
    .title
      position: absolute
      top: 0
      left: 10%
      z-index: 40
      width: 80%
      no-wrap()
      text-align: center
      line-height: 40px
      font-size: $font-size-medium-x
      color: $color-text
    .bg-image
      position: relative
      width: 100%
      height: 0
      padding-top: 70%
      transform-origin: top
      background-size: cover
      .play-wrapper
        position: absolute
        bottom: 20px
        z-index: 50
        width: 100%
        .play
          box-sizing: border-box
          width: 135px
          padding: 7px 0
          margin: 0 auto
          text-align: center
          border: 1px solid $color-theme
          color: $color-theme
          border-radius: 100px
          font-size: 0
          .icon-play
            display: inline-block
            vertical-align: middle
            margin-right: 6px
            font-size: $font-size-medium-x
          .text
            display: inline-block
            vertical-align: middle
            font-size: $font-size-small
      .filter
        position: absolute
        top: 0
        left: 0
        width: 100%
        height: 100%
        background: rgba(7, 17, 27, 0.4)
    .bg-layer
      position: relative
      height: 100%
      background: $color-background
    .list
      position: fixed
      top: 0
      bottom: 0
      width: 100%
      background: $color-background
      .song-list-wrapper
        padding: 20px 30px
      .loading-container
        position: absolute
        width: 100%
        top: 50%
        transform: translateY(-50%)
</style>
